27

Welcome to the field of network engineering! DTP stands for Dynamic Trunking Protocol and is crucial to the commands below. It is also Cisco proprietary. switchport mode access - Always forces that port to be an access port with no VLAN tagging allowed EXCEPT for the voice vlan. DTP is not used and a trunk will never be formed. switchport nonegotiate - ...


19

"Bus" is connection to 16Gbit/s bus that is common to legacy 6500 architecture. Crossbar and dCEF mean the connection from the LC (line card) is using switch fabric (separate SFM module for Sup2, integrated switch fabric chip on Sup720 and Sup2T). Crossbar means the connection is from the line card that doesn't have distributed processing capabilities (no ...


18

CEF is Cisco's word for their FIB. When in L3 switch you do 'sh ip cef', none of this information is actually used to push the packets at all, this is just software trie which is used to populate the hardware ASIC. CEF is just term Cisco uses to describe their optimize data storage/retrieval code, it is not specific technology with specific function. In ...


9

Does this mean CEF isn't used by edge routers and edge L3 switches? Is CEF's usefulness limited to the LAN? CEF is useful because it permits a router to quickly rewrite the Layer2 information during Layer3 forwarding operations. WAN routers must rewrite Layer2 header information just like LAN switches do... CEF is extremely useful to both types of router. ...


8

Quick rule of thumb: dCEF > Crossbar > Bus If you have a line card operating in bus mode, then your active supervisor will operate in bus mode as well. This can impact the performance of your 6500/7600. You may want to look into the modules running in bus mode. Many of these modules have been EoL for some time and should probably be replaced. We ...


8

NAT can of course use CEF. This is from Cisco's own guide over here: http://www.cisco.com/en/US/tech/tk648/tk361/technologies_q_and_a_item09186a00800e523b.shtml Q. What kind of routing performance can be expected when using Cisco IOS NAT? A. Cisco IOS NAT supports Cisco Express Forwarding switching, fast switching, and process switching. For 12.4T ...


7

Access - Basically is for end devices, and hard set. If you put a trunk on this, it wouldn't work. dynamic - Makes the interface actively attempt to convert the link to a trunking link. The interface becomes a trunk interface if the neighboring interface is set to trunk, desirable, or auto mode. auto - same as dynamic, but doesn't actively attempt to convert ...


7

With circuit switching, you have a 1-to-1 circuit with some predefined channel capacity which is guaranteed. For it to work, you must first establish a circuit/connection before you send any data, and break the connection after. With packet switching, it's somewhat like the local post office - you bring the packets, send them, and let the other devices ...


4

Shared memory and port buffering are not mutually exclusive: Packets payloads will be stored in shared memory prior to being transmitted (think how inefficient it would be to store a broadcast frame 48 different times in order to flood it out each port). Port buffering comes into play when multiple packets arrive at the switch from different ingress ...


4

If the frames entering the switch are using a 1G port, but are being forwarded out a 100M port, then it's likely that frames are coming in faster than they are going out. So they need to be buffered until they can all be transmitted.


4

A "circuit" doesn't necessarily mean the same thing as a physical electrical circuit. That's where the term started out, but when various multiplexing schemes were invented, such as TDM, "circuit" acquired the meaning of a certain channel or slot inside the physical connection. In the T-carrier system, for example, the unit called the "circuit" is the 64kbps ...


3

Check out this page for the info you require, plus a list of references from the Cisco site; http://null.53bits.co.uk/index.php?page=6500-7600-chassis-architecture


3

In circuit switched connection: a connection is always established from end to end before transferring data. in the general case the connection has fixed capacity for the whole duration of the connection even if you don't transmit any useful data and at the same time other connections can;t use your capacity the whole capacity is guaranteed the speed of ...


3

Switchport puts a port into layer2 mode (ip routing disabled for the port). You cannot assign an IP address to a L2 port, only to the VLAN the L2 port belongs to. The options after switchport is used to set port operation mode for VLAN trunking. Cisco IOS command reference "no switchport" enabled L3 features on the port, you can give it an IP address, ...


2

What is the difference between Switch Fabric Capacity and Forwarding Rate of a switch? Switch Fabric Capacity: It usually means the maximum rate the hardware can move information between cards/ports. However it does not account for time spent looking up output port for frames and packets, for instance. Forwarding Rate: It usually means the maximum rate the ...


2

In a hub, all the ports are electrically connected, and only one device at a time can talk on the wire. If more then one device talks at the same time, it creates a collision, so hub ports are all half-duplex. In a switch, each port is isolated, and traffic from one port is selectively sent to other ports, so there are no collisions in the switch. Unlike a ...


2

The mode/speed is configured on the switch port! So you could have 12 ports in half-duplex(for devices that don't support full-duplex) and 12 ports in full-duplex. On the assumption that you're on a physical "star topology", those in "half" won't disrupt the others.


2

Configure each VLAN with "no shutdown." Make sure that the VLANs are active. "Conf t" and the type "vlan 2" and see if that brings the VLAN up. Do this with the rest of the VLANs. Make sure that each switch has all VLANs configured, or else you won't be able to trunk those VLANs. This should solve your problem...


2

A broadcast frame is forwarded to all switch ports but the one it was received from. When several switches are connected to each other the broadcast will eventually reach all ports in this broadcast domain. That is unless you've got VLANs set up. VLANs separate the network into distinct broadcast domains that do not communicate with each other on layer 2 (...


2

You don't mention brand of the switch, any management software, or any configuration (in particular how that interface was previously configured), so I can only answer generically. Most default switch MAC address tables have a relatively low timeout to age out entries. Just because you are only seeing 19 devices from the same VLAN on a port currently doesn'...


2

This is a lot more complex than just a software-selectable forwarding option - and is true not only for Cisco but most other vendors. First of all - store-and-forward vs cut-through generally isn't software selectable on most switches. It's potentially available if the speeds of ingress and egress ports are equivalent but as soon as multiple speeds are ...


2

It rather depends on what is real. 24V 6.5W is not 24V 0.5 A - but I think the latter number is just what the default (passive) POE power brick is, and they are oversized somewhat by default. 24V 0.5A would be 12W. 24 of those would be 288W and require the 500W switch. 6.5W X 24 ports would be 156W and the 250W would be fine. Actual data update - not ...


2

I don't know the exact model you are using, but the specs I read say 48V @.5A. That's 24 watts (and is more inline with similar APs) 23 ports @ 24W = 552 Watts. So, no, you can't power all the devices. Also don't forget to account for 50-75 watts for the switch itself.


2

On switch 2, the client ports are on VLAN 100 and 200 (not 10 and 20). EDITED to include Marc Luethi's comment: On ESW2, the switchports where R1, R2, R3 are connected are without spanning-tree portfast. That will leave these switchports in LIS/LRN spanning tree state for at least 30 seconds after they get 'line protocol up'. That might be long ...


2

This question has been asked at least a dozen times. We can only guess why the spec says what it says -- no one here wrote it. Despite what the spec says, no one does that -- "ingress filtering" is always enabled on a VLAN aware switch: if vlan 20 isn't not assigned to the port, anything tagged 20 will be dropped. As for untagged traffic, yes, it too (...


1

An access port that receives tagged traffic will drop the tagged frames.


1

Your problem is that the VTP passwords don't match. On the non-working switch: MD5 digest : 0xB9 0x07 0xEE 0xE3 0x27 0xEC 0xF7 0x33 0x98 0x81 0x0A 0xA3 0x32 0xE9 0xD2 0xDF On the working switch: MD5 digest : 0x39 0x28 0x36 0x47 0xDE 0xDC 0xBE 0x26 ...


1

You still need to configure the VLAN 3 SVI on the L3 switch. You also need to set trunk mode and encapsulation on Fa0/24 of all three L2 switches.


1

A message could be circuit switched or packet switched. You would probably classify message switching as an application layer construct. Packet switching can break a large message into smaller packets to be sent, but a message may be small enough to fit into a single packet, too. A circuit could carry a message over a circuit switched network. It's kind ...


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